The invention relates to serum thymic factor peptide analogs of the general formula I. EQU A-Gly-Gly-Ser-Asn-B-C-NH-R (I),
in which A is pGlu, Gln, Ala-Lys-Ser-Gln, pGlu-Ala-Lys-Ser-Gln or Gln-Ala-Lys-Ser-Gln, B and C are the same or different and are each Gly, Phe, Leu, Ala or a direct bond, and R is H, an alkyl with 1 to 6 carbon atoms or a 2-phenylethyl group. The invention also relates to a process for the preparation thereof.
Thymic agonists, either the natural hormone isolated from thymus or its synthetic analogs, have recently been adopted in the treatment of immunodeficiency for increasing the patients' immune response, e.g. in systemic diseases lupus erythematodes, myasthenia gravis, infantile asthma, and also in certain neoplastic diseases.
Thymic factor analogs are known. G. Tsukamoto et al., J. Protein Chem. I, 305-15 (1982). The search for such analogs has heretofore focused on the modification of the natural serum thymic factor molecule either inside the amino-acid sequence (pGlu-Ala-Lys-Ser-Gln-Gly.sub.2 -Ser-Asn) or at its N-terminus (i.e. the left-hand end). Surprisingly, not a single attempt of modification or prolongation at the opposite, C-terminus (the right-hand end) of the sequence has been reported.